Insecticide



Patented May 27, 194i QFFI msncrr ilil: E

No Drawing. Application February 25, 1939, Serial No. 258,468

(Ci. rev-=30 3 (lies.

This invention relates to insecticidal composi tions and particularly to the use of certain substituted phenyl benzyl ethers and thio ethers as the active principle thereof. It is a continuation-in-partof copending application Serial No. 141,927 filed May 11, 1937, now U. S. Patent No. 2,159,025, issued May 23, 1939.

The object of the invention is to provide improved insecticidal compositions of general application which can be used in low concentration to control pests without injury to plant foliage. A further object is to provide an organic insecticide of the so-called stomach type to be used in place of lead arsenate, etc. against chewing insects such as bean beetles, etc.

A still further object relating to and growing out of the accomplishing of the foregoing objects is to provide an eiiicient method for the preparation of phenyl benzyl ethers in high yields.

The phenyl ethers and benzyl ethers have heretofore been proposed as insecticidal principles. However, they have never been used extensively for the purpose because of their relatively low toxicity as compared to other known insecticidal principles and because of the severe plant injury that results from their use in sufficient quantities to be effective against insects. It has now been found, however, that the introduction of certain substituents into either the phenyl or benzyl group has the effect of greatly reducing the corrosiveness of phenyl benzyl ethers to plant foliage, while in many instances increasing the toxicity of the base compound. By a series of many hundred tests on phenyl benzyl ethers having various substituents in the phenyl and/or benzyl nucleus, it has been established that substituents having an atomic or relative group weight of at least 30 and which are not themselves corrosive, such as strongly acid or basic groups and the phenolic hydroxyl group, either greatly reduce plant foliage injury as compared with equal proportions of the unsubstituted compound or so greatly increase the toxicity that by using smaller dosages, plant injury can be avoided while maintaining effective insect control. Substituents of a total relative weight less than 30 are apparently too small to be effective.

Among the substituent groups that have beenfound to produce this effect may be mentioned the alkyl groups of more than 2 carbon atoms, the alkylene groups-of similar carbon content, hydroaromatic groups, aralkyl groups, alkoxy groups, aryloxy groups, -acyl groups, halogen atoms, nitro groups, amino groups that have been neutralized, acylamino, alkylamino and aralkylamino groups, and carboxyl and sulfonic groups that have been neutralized as by being converted to a salt, ester, or lactone group. It has also been found that when the single aromatic ring of either the benzyl or phenyl group is replaced with a polynuclear aromatic group such as the naphthyl radical, the second ring produces the efiect of a substituent group. Such polynuclear groups are accordingly hereinafter considered as substituted phenyl groups. The substituent group may be in either the ortho, meta, or para position to the CH2O' linkage but preferably is in the para where its influence in stomach poisons is generally the greatest. In compounds to be used solely as contact insecticides, the substituent in the ortho position is preferred. A plurality of substituents either similar or dissimilar and either situated on the one or on both aromatic rings, is included. Compounds with substituents in the methylene group are also included.

These compounds may be made in any of the known methods all of which in principle involve condensing in an alkaline medium the properly substituted phenol with benzyl chloride containing the desired substituents, if any, in the benzyl group. An improved method that has been found particularly satisfactory andwhich is a feature of this invention is the utilization of dimethylaniline in amounts substantially less than equimolecular with the benzyl chloride in conjunction with an alkali metal hydroxide as the condensing agent. In general this improved method comprises mixing the phenol or the sodium salt of the phenol being condensed, a slight molar excess of the benzyl chloride, dimethylaniline in amounts approximately one half the molar quantity of the phenol or benzyl chloride, and an amount of alkali metal hydroxide equivalent to the amount of benzyl chloride in aqueous emulsion, heating until reaction is substantially complete, filtering, and washing, and recrystallizing or otherwise purifying the product. The proportions here given are not critical but rather are those that have been found to give in general the most economical yields. Larger or smaller amounts of dimethylaniline may be used. The following examples are given to illustrate this method of preparation, wide variations in them being permissible.

EXAMP LE 1 Preparation of C'sHsCH2OCsH4NO2-4 A mixture of 3360 g. (14 mol) of 81.8% para- 7 l. of water.

nitro-sodium phenolate dihydrate, 2050 g. (15.4 mols) of benzyl chloride, 848 g. ('7 mols) of dimethylaniline, 56 g. (1.4 mol) of sodium hydroxide in 10 1. of water, was heated on a boiling water bath for 6 hours, with stirring. It was allowed to stand overnight, and then was filtered. The filtrate was 'neutral to litmus. The cake was ground and washed with 609 cc. ('7 mols) of concentrated hydrochloric acid in 3 l. of water, and

then with 400 cc. (4.7 mols) of acid in 10 l. of water. The solid was washed twice with 2 l. of methanol, once with 3 l. of petroleum ether (B.

P. 60-100 C.) and then recrystallized from iso- EXAMPLE 2 Preparation CaH5C'H2OC'sH4C'sHs-2 A mixture of 2040 g. (12 mols) of orthophenylphenol, 1670 g. (13.2 mols) of benzyl chloride, 530 g. (13.2 mols) of sodium hydroxide, 727 g. (6 mols) of dimethylaniline, in 1. of water, was heated to 100 C. and stirred at this temperature for 4 hours. The mixture was allowed to cool overnight and the top aqueous layer was siphoned off. A mixture of 3.5 l. of ethylene dichloride and 3.5 l. of water containing 50 g. of sodium hydroxide was added to the bottom layer, and after stirring, allowed to separate. The bottom layer was washed with 7 l. of water and then three times with 520 cc. (6 mols) 01 concentrated hydrochloric acid in 3.5 l. of water. The bottom layer was washed three times with The ethylene dichloride solution was dried over calcium chloride, concentrated, dissolved in 6.3 l. of methanol, and cooled to 0. The crystalline product was filtered off and airdried. The total weight was 2880 g., or 92.3% of the theoretical yield. Melting point 42-3 C. When 363 g. (3 mols) or 0.25 molecular equivalents of dimethylaniline was used, the yield was only 79%.

' Exmru. 3 Preparation of C6H5CHzOC'sH4C'(CHs)a4 A mixture of 150 g. (1 mol) of paratertiarybutylphenol, 62 g. (0.5 mol) of dimethylaniline, 139 g. (1.1 mol) of benzyl chloride, 44 g. (1.1 mol) of sodium hydroxide in 540 cc. of water, was stirred and heated on a boiling water bath for 4 hours. The mixture was rapidly cooled and to it was added50 cc. (0.5 mol) of concentrated 1wdrochloric acid. The solid was washed twice by melting in the presence of 0.5 mol of hydrochloric acid in 700 cc. of water, and then washed twice with water. It was recrystallized from 350 cc. of methanol, giving 200 g. or 83% yield. Melting point 64 C.

EXAMPLE 4.--Preparation of 4-NO2CH4CH2- QCH4C(CH:):--4.-Crude paranitrobenzyl bromide was prepared by the method of Org. Syn. XVL, 54. 5

A mixture of 400 'g. of this crude material (1.33 mol) 200 g. (1.33 mol) of paratertiary butylphenol, 60 g; (1.5 mol) of sodium'hydroxide in 1 l. of water, was heated on a boiling water bath and stirred for 4 hours. After cooling overnight, the resulting solid was transferred to a Biichner tunnel and washed with 100 cc. of 50% methanol and with 100 cc. of 75% methanol.

product was then recrystallized from 800 cc. of methanol twice as light tan crystals melting at The yield of 4'-nitrobenzyl 4-tertiarybutyl phenyl ether was 311 g., or 82%.

The best method of using these phenyl benzyl ethers ininsecticidal compositions will depend to a large extent on the particular insect or class of insects which is being combated When used to control chewing insects such as the bean beetle they may be applied as either a dust or a spray in which the active ingredient varies from 0.05 to 5% of the total. The dusts are readily prepared by dissolving the ether in a suitable solvent such as acetone, mixing the proper amount of solution with an inert powdered substance such as talc, lime, etc. and drying while stirring the powder. Suitable formulae are the following- Parts by weight (a) Active ingredient 1 Talc or lime 98 Spreader (cetyl dimethyl ethyl ammonium ethyl sulfate) 1 (1)) Active ingredient 1 Alum sludge 48 Limp 4g Soy bean oil 3 Sprays to combat chewing insects can be made by applying a larger quantity of the active ingredient to a powder adding an emulsifyin a ent and dispersing in sufiicient water to reduce the quantity of active ingredients in the final spray to the desired concentration. A suitable formula for this type of spray is-- Parts 1 part active ingredient deposited on 2 parts magnesium carbonate 3 YA commencial emulsifying agent sold under Parts .25 part active ingredient and .25 part emulsifying agent dissolved in .50 part pine oil 1 Water 100-300 Spray used to combat flying insects such as common flies, mosquitoes, etc. can be made by merely dissolving the proper amount of active ingredient, 1-5%, in an organic solvent such as kerosene to which a spreading agent may be added if desired.

The tables given below show the results of a number of tests using variously substituted phenyl benzyl ethers in combating the more common insects. There is also included for purposes of comparison the results obtained when the unsubstituted compound is used.

Table I gives the results 01' toxicity tests 011% dusts of sprays against bean beetle larvae. These tests were made under controlled temperature, humidity and light conditions. The bean plants were sprayed or dusted 24 hours before the Mexican bean beetle larvae were introduced. Counts were made at the end of 96 hours." At

a least three experiments were run on ea A small amount of black oil filtered through. The 75 on com pound and the figures given are the average.

Checks were made in each case with magnesium In the foregoing tables the tests summarized arsenate. I used the substituted phenyl benzyl ether-s as I Table 1 Mg arsenate Formula Plant Lul. Kill In ap.

Kill Incap.

' Percent Percent Percent Percent CsHgCHaO CaHs. Severe- 13 6 40 3 CsHsCHaOCsIL cflzgri-.. N" 76 40 3 CuHsCHaOCaH C CH: refill-4-.- N 80 3 40 3 OH OHzOCaH4CH(CH:)r-4..; N0 73 13 40 3 CaHsCH2 sH4CoHr- 46 2% 43 23 CsH5CH20CBH4C14--- 60 6 43 23 CsHgCHgOCslLNOa-i N0..--- 83 0 40 3 CsH5CHaOCsH2(2, i}(N02)34-C(CH;) CH:C(CHl)s) N0 53 10 35 13 CqHgCHaOCsHaCHz-Q-NOH-.. 0 60 30 30 8 CgHsCHzOCqH COCQHr-4 73 a 30 6 CaHsCHgOCdH3( 2N02)B0aNHsCuH4C1-4 16 23 30 6 4-NO2C0H CHOC4H4C(CH3)r-4 93 3 35 13 4-NO5CeH4CH2OC5H4CHs-4 66 ..t 35 13 1C uH7CH OCsH5 30 23 30 6 eHs)rCHOCsHs 0 20 35 3 Table 11 gives he r s lt of a Similar ri s f stomach poisons. The tables that follow show tests performed on bean beetle adults. These the results of tests in which they are used as tests were made under the same conditions given contact poisons. Table IV shows their toxicity for Table I excepting that the bean beetle adults against red spiders. In all these tests the inwere used instead of the larvae. secticide was applied as an emulsion spray in Table II Mg arsenate Formula Plant inj.

Kill In ap.

Percent Percent Percent CsHsOHiOCsHs. Severe C(lHsQHEOCSEiCHH Fatal-.. 13 q 23 CsHsCHzOCsEhCHg-G U. 0.... 10 CaHsCHzOCsH4C (CHQH N0 20 G 15 CuHsCHaOCsH C(CHa)aCH:CH:- N0 43 3 15 CsHsCH20CsH4C (CHshCHaC (CH:)s-4 N9 13 0 20 CsH5CH2OCoH4COCHa-4- Sllght-.- 10 10 16 CeHgCHaOCaHflaHs -l 20 10 16 C5H CH2OC$H4C Slight. 43 6 16 CsHsCHlO CsHiN 02-4 10 16 CsH5CH30C5H4NO:2 Slight--. 23 3 16 Co sCH2OC10H11... d0 16 10 16 CuHgCHzOCmH7-2.-.- N 16 3 16 1, 3(CsHsCH20)aCsH4 N0 13 0 16 (CsH5CH:OCsH4)2C(CH3)2 N0- 15 0 10 CsHsCHaOCaHsN Or2Cl-4 No 23 13 16 CsH CH2SCeH4N 02-4- N0 26 6 16 CsHsCHaSCeHa(NO2)z-2, 4... N0 10 0 10 CsHsCHaOCsILNHCOCHa- 20 16 16 CsH5CH20C$H4CO0Z!l/2 20 5 10 CsHgCHzOCdLSOsNHaCsEhCHr- 13 0 16 4NO:C0H4CH3OCAHA 36 6 10 4-NO2CsH4CHaOCoH4NOa-2- I N 16 3 13 30 13 13 16 0 26 13 0 33 3 15 30 5 50 5 25 5 30 6 30 3 3-N O:4CH3OC5H3CH2OC5H5 N0 30 13 30 3 1--CmH7CHzOCsHCl-4 N0 35 I 10 25 5 1-C1fl1CH2OCsH4CsHs-2- N0 30 10 30 3 2-C1oH CH:OOsH4C(CH;;r-4 Slight..- 30 0 36 3 2 C 0HCH3OC0H4C CH =CH=C (CH3):-4 N0 26 3 36 3 2C1oHCHnOC6 AC 5- 20 5 35 5 Table 111 shows the effectiveness of the new which the toxic material being tested was dilut-' insecticides against cabbage worm larvae. The ed 1:1200 times unless otherwise indicated. At procedure was the same as for Tables I and II this dilution no foliage injury was observed with except the test organism was the larva of the any of the materials tested. The tests were made diamond-back cabbage worm. V by spraying the emulsion under standard condi- Table III Mg atsenata Formula Plant 1111. Kill Kill 7 Incap.

' Percent CoHsCHzOC Severo.- C HsCH0CaHlOCH:):-4- N 100 CsHgCHaOCslLC CHDICIHP N0 (lsHsCHzo 4 5- No 77 CsHsCHaOCoHfll-L. Blight.-- 83 CsHsCH2OCoH4NO2-4- No 43 CsHsCHsOCaH:(N0:)s-2, 6- C(CH:)1CH:C(CH1)x-4 NO--- 93 4NOzCeH4CHaOCsH|C(CH No 53 1 Lead arsenate used in check in place oi magnesium arsenate.

tions on foliage infested with red spiders (Araneida). The host plants were ageratum, bean, and cabbage. The plants were allowed to stand for 24 hours and then counts were made on five pieces of the plant for each test. The figures given are the average percent kill.

Table IV Formula Kill Percent CeHsCHIOCuHs 26 saaaaeaaaeasaaasae:

2 (CQH)2C(OC:H5)OC5H4C14 Table V summarizes similar tests against mealy bugs. The tests were conducted in the same manner as in Table IV excepting that the organisms were mealy bugs and the host plant coleus.

Table V Formula CaHsCHzOCeHs CoHsCHlOC ILCHQ-El 4N O:CH4CH:O CeHACHr-3 Table VI summarizes tests performed as in 5 Tables IV and V on aphis infesting nasturtium and cabbage plants.

Table VI Formula Kill Percent CeHlCHaOCcHs ClH|CH:OCoH4CH:-3 CuHlOH1OCaH4OH 2.. CCHIOClHAOCHS-2 (dllu mmomommcmclkcm z. CIHICHaOCmHr-l (dilution 1:241)

Finally, Table VII gives data on fly tests conducted by the standardized procedure of the approved Feet-Grady method. In these tests a 2% solution of the indicated phenyl benzyl ether in kerosene was used.

Additional compounds that have been tested and which show a. much reduced corrosiveness to plants as compared to the unsubstituted phenyl benzyl ethers without sacrifice of toxicity are- From the data herein contained it is apparent that those phenyl benzyl ethers having a subs'tantially neutral substituent of atomic or relative group weight of at least 30 are less corrosive to plants than the unsubstituted or less highly substituted ones. Also that they have a. wide range of usefulness in combating insect pests. Additional substituent groups and other ways of using those herein disclosed will be apparent to persons skilled in the art. It is intended that such modifications as do not depart from the basic concept of the invention are to be included in the appended claims.

I claim: I

1. An agricultural insecticidal composition adapted for use on living plants containing phenyl benzyl ether substituted in at least one of the benzene rings with a halogen having a relative I group weight over thirty.

2. An agricultural insecticidal composition adapted for use on living plants containing phenyl benzyl ether substituted in at least one of the benzene rings with chlorine.

3. An agricultural insecticidal composition adapted for use on living plants comprising a compound from the group consisting of phenyl benzyl ether, phenyl benzyl ethers having an alkyl substituent on the phenyl group, and phenyl benzyl ethers having an aromatically bound nitro group, said compound having at least one halogen substituent of a relative weight above thirty at- 15 tached to an aromatic ring.

WILLIAM F. HESTER. 

